Basstracker cavitating, looking for suggestions

[rocko]

Hello All,
I have a 1998 Basstracker 120Hp sport jet. We have owned it since 2000. Its been rock solid for us.
In the past 5 years it has been cavitating more than normal. I replaced the ride plate seal, the wear ring and impeller. It certainly improved after that.

The last 2 seasons its been getting worse again where the water has to almost be flat to ride without it "slipping". Took it out this past weekend and was having the same issue with a little wind and it would "Slip". If i am solo in the boat i need to pretty much sit in the middle of the boat.
The boat is aluminum and is beat up from hitting rocks in the river.

Is there something I can do to fix this. I like to DIY, so looking for suggestions of things i can look at. There is a fin on the back under the output, should i bend that down? The ride plate is pretty good shape.

Thanks for reading and looking forward to some chatter.

Thanks
Bob

 

[zipper]

Pictures of your description might help. Lets see that fin and how it could effect the thrust. Impellor and wear ring too.

 

[rocko]

I will when i get home from work. thank you.

 

[Julian]

What is the clearance between the impeller and wear ring? You can look up the Yamaha specs...but that clearance must be within spec (very small gap!)

 

[rocko]

Got under the boat and found this.

 

[Julian]

Got under the boat and found this.

Yeah.....that would be a problem!

 

[zipper]

Looks like you found the cavitation issue. Glad you found it so quickly.